The invention relates to a fuel supply system for internal combustion engines provided with an intake manifold, wherein an air flow sensor and a manually controlled throttle element are arranged in tandem and the air flow sensor is rotatably mounted about an axis which extends in the direction of flow and is moved against a reset force in accordance with the amount of flowing air and during the course of which the air flow sensor adjusts the movable portion of a valve disposed in the fuel supply line in order to meter an amount of fuel that corresponds to the amount of air.